Bugfixes to get Migration working on MySQL and MariaDB (#4551)

* Bugfixes to get Migration working on MySQL

Signed-off-by: objec <objecttothis@gmail.com>

* MariaDB compatibility fixes

- Drop foreign key constraints before making charset changes
- Fix dropAllForeignKeyConstraints helper function.
- Added `IF EXISTS` to DROP statements
- Do not try to readd FK constraints for tables which were dropped.
- MariaDB 11.8.x changes the default implicit collation to uca1400 which breaks the IndiaGST migration, et. al. Explicitly declare utf8_general_ci in affected migrations.

Signed-off-by: objec <objecttothis@gmail.com>

* Fix changes which break MySQL migrations

- MySQL does not support IF EXISTS in foreign key constraints. Since the PHP is now handling dropping those constraints, these lines are redundant. Remove them.

Signed-off-by: objec <objecttothis@gmail.com>

* Resolve code review recommendations

- Add try/catch around DB connect statement
- Heed result of execute_script function and throw an exception on failure.

Signed-off-by: objec <objecttothis@gmail.com>

* Refactor out duplicate code

Signed-off-by: objec <objecttothis@gmail.com>

* Initialize array variable causing potential issues

Signed-off-by: objec <objecttothis@gmail.com>

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Signed-off-by: objec <objecttothis@gmail.com>

app/Database/Migrations/sqlscripts/3.3.0_paymenttracking.sql

@@ -12,7 +12,7 @@ CREATE TABLE `ospos_sales_payments` (
   `reference_code` varchar(40) NOT NULL DEFAULT '',
   PRIMARY KEY (`payment_id`),
   KEY `payment_sale` (`sale_id`, `payment_type`)
-) ENGINE=InnoDB DEFAULT CHARSET=utf8;
+) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_general_ci;
 
 INSERT INTO ospos_sales_payments (sale_id, payment_type, payment_amount, payment_user)
 SELECT payments.sale_id, payments.payment_type, payments.payment_amount, sales.employee_id